1. Field of the Invention
The present invention relates to an apparatus and a method for applying a coating liquid or a developing liquid on a surface of a substrate such as a semiconductor wafer, a glass substrate, or the like so as to form a coating film or the like.
2. Description of Prior Art
There have been known apparatuses disclosed in Documents 1-6 as an apparatus for forming a coating film having a uniform thickness on a surface of a substrate.
Document 1 has disclosed that a resist liquid is supplied with a predetermined width from a nozzle to a surface of a glass substrate, in which the nozzle is movable in a short side direction of the glass substrate, and the resist liquid supplied with a predetermined width is leveled to have a uniform thickness with a plate (squeegee) which moves in a long side direction of the glass substrate.
Document 2 has disclosed that a developing liquid is supplied from a nozzle to a surface of a substrate which is horizontally spun by a spin chuck, and the developing liquid is applied onto the surface of the substrate to have a predetermined thickness while the developing liquid is received by a spreading member (squeegee) provided to keep a minute distance from the surface of the substrate.
Documents 3 and 4 have disclosed that a substrate is placed into a recessed portion provided in a substrate stage so as to make the upper surface of the substrate stage and the upper surface of the substrate in the same plane, and a coating liquid is supplied from a slit nozzle to the upper surface of the substrate stage including the substrate so as to form a coating film having a predetermined thickness on the surface of the substrate.
Document 5 has disclosed that while a tray having a recessed portion for accommodating a substrate is transferred, a coating liquid is supplied to a substrate placed in the recessed portion by using a slit nozzle, a coating film is formed by moving the substrate together with the tray, and thereafter the tray alone is moved to a cleaning station and a drying station.
Document 6 has disclosed that a pre-dispensing area is provided adjacent to a recessed portion for accommodating a substrate in a similar tray structure to Document 5.
[Document 1] Japanese Patent Application Publication No. 7-289973
[Document 2] Japanese Patent Application Publication No. 8-022952
[Document 3] Japanese Patent Application Publication No. 2001-269610
[Document 4] Japanese Patent Application Publication No. 2002-59060
[Document 5] Japanese Patent Application Publication No. 2003-245591
[Document 6] Japanese Patent Application Publication No. 2004-209340
However, in the method as disclosed in Document 1, since the film thickness becomes large at the starting point of the coating, it is impossible to form a coating film entirely to the periphery of the glass substrate.
In the method as disclosed in Document 2, since the developing liquid is spread by spinning the substrate, the liquid moves toward the outside of the substrate and the amount of the liquid tends to be less in the center.
In the case of using a slit nozzle as in Document 3 and Document 4, it is difficult to supply a coating liquid with a uniform thickness in a side direction of the substrate. For example, if the width of the slit nozzle is larger in a longitudinal direction of the slit nozzle even partly, the coating liquid will be supplied excessively from that part. Also, if there is variation in the pressure during the coating by the slit nozzle, the amount of the supplied coating liquid will also be varied. Thus, the structure of the slit nozzle requires delicate adjustment, which makes it difficult to handle.
Since Document 5 also uses a slit nozzle, its handing is difficult. In addition, this technique has a disadvantage in terms of space because the cleaning station and the drying station are separate from each other. The technique disclosed in Document 6 has the same drawback as in Document 5.